1. Field of the Invention
This invention relates to mass transit vehicles and more particularly to a stairway structure for such vehicles which will accommodate varying conditions of passenger loading and embarkation.
2. Description of the Prior Art
Considerable difficulty is experienced in adapting mass transit vehicles to variations in passenger off and on loading facilities. The situation is particularly acute where the mass transit vehicle must accommodate passengers which enter from a street level and also from subway or elevated platforms.
While various types of movable stairway structures have been developed these structures suffer from various deficiencies. For instance, a stairway structure to be operable in a practical sense in such mass transit vehicles must be capable of movement between its various operative positions while the vehicle is in motion with the doors closed and while passengers stand on the stairway surfaces. This means not only that the surfaces must be maintained during movement in a horizontal plane but also all working parts must be so positioned as not to contact the passengers and large gaps between the movable step members and the supporting or surrounding structure must be avoided.
Accordingly, it is a primary object of this invention to alleviate the aforementioned difficulties of the art by providing a new and novel movable step assembly.
It is also an object of this invention to provide such a step assembly which is capable of facilitating passenger movement to and from at least two different elevations such as a loading platform and a street level.
It is a further object of this invention to provide such a step assembly which will be safely operable while the vehicle is in service and even while passengers are standing on the step assembly.
An object of this invention is to provide for purely vertical movement of the steps so that the steps may be raised and lowered during movement of the vehicle with passengers on said stairs and while the vehicle doors are in a closed position.
As an additional object of this invention, a step assembly is provided which has no exposed linkages or protruding parts and has no large gaps between the movable steps and the surrounding structure in which passengers or their clothing might be caught and serious damage caused.
It is also an object of this invention to provide such a step assembly which may be simply and inexpensively constructed and easily maintained and very reliable in operation.
Additional objects and advantages of this invention will be set forth in part in the description which follows and in part will be obvious from the description or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.